arm64: dts: rockchip: include opp dtsi for rk3399 firefly

Add opp tables for cpu cluster0 and cluster1 by including
rk3399-opp.dtsi.

Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>